In a machine tool or a dimension measuring instrument, a movable machine part, such as a work table, slides on a guide surface of a stationary base. The sliding movement of the movable machine part is driven by a drive source, such as a motor. In order to acquire a smooth sliding movement of the movable machine part on the guide surface of the stationary base, two conventional guide mechanisms have been employed. One of the conventional guide mechanisms is well known as a dynamic pressure type guide mechanism, in which the movable machine part slides on the guide surface of the base while directly contacting the guide surface via a film of a lubricant, such as a lubricating oil. The other of the conventional guide mechanisms is a static pressure type guide mechanism disclosed in, for example, U.S. Pat. No. 3,711,167, in which mechanism a pressurized fluid is supplied between the slide surface of the movable machine part and the guide surface of the base so that the static pressure of the pressurized fluid supports the entire load of the movable machine part. In that arrangement, no direct contact of the slide surface of the movable machine part with the guide surface of the base occurs. However, with the dynamic pressure type guide mechanism, the sliding movement of the movable machine part usually is subject to a rather large frictional force which increases in response to an increase in the load applied to the movable machine part. Further, since a so-called "stick slip" motion occurs during the sliding movement of the movable machine part the, accuracy of the sliding movement is low.
With the static pressure type guide mechanism, collection of the pressurized fluid is difficult if the pressurized fluid is a pressurized liquid. Further, if a pressurized liquid is employed, unfavorable an generation of heat occurs during the sliding movement of the movable machine part on the guide surface of the base, due to the viscosity of the liquid. On the other hand, if the pressurized fluid is a pressurized gas, such as pressurized air, a steady sliding movement of the movable machine part is not acquired. In addition, not only the pressurized liquid, but also the pressurized gas, ineffectively damp the vibration of the movable machine part.
In order to obviate the above-mentioned defects encountered by the conventional dynamic pressure and static pressure type guide mechanisms, a load-compensated type guide mechanism has been developed, and one example thereof is disclosed in Japanese Laid-open Patent Application No. 1979-126850 by the same applicant as the present application. However, the applicant has invented a novel load-compensated type guide mechanism which has an improved performance over that disclosed in the above-mentioned application.